Responsive Air Launch Using F-15 Global Strike Eagle

Transcription

1 4th Responsive Space Conference RS Responsive Air Launch Using F-15 Global Strike Eagle Timothy T. Chen, Preston W. Ferguson, David A. Deamer, and John Hensley The Boeing Company 4th Responsive Space Conference April 24 27, 2006 Los Angeles, CA

2 AIAA-RS RESPONSIVE AIR LAUNCH USING F-15 GLOBAL STRIKE EAGLE Timothy T. Chen, Preston W. Ferguson, David A. Deamer, and John Hensley The Boeing Company, Huntington Beach, CA ABSTRACT A near term military need exists for a capability to execute global strike, responsive spacelift and space control missions. An innovative solution concept was developed based on integrating offthe shelf components to provide this capability, while avoiding technology development risk. The paper presents a concept that would utilize an F-15E with minimal modifications to provide a reusable first stage for the F-15GSE (Global Strike Eagle). The upper stages of the F-15GSE would consist of currently available solid rocket motors packaged to meet the mission requirements. The F-15GSE concept could provide an all azimuth capability from a single CONUS base while reducing the Delta-V required for orbital insertion by 5,000 fps versus a ground launch rocket system. Advantages of an F-15GSE system include: increased mission flexibility, rapid response time without deployment of assets, multiple basing options and covert launches. Operational missions could be completed within two hours while on alert status with minimal infrastructure from CONUS or remote bases. Initially this concept could provide a low-cost demonstration of global strike, while military operational capability could be met with an expansion of fleet size. The F-15GSE would be capable of global reach with delivery of munitions including the Common Aero Vehicle (CAV) and also provide a LEO launch capability for microsats. Planned future upgrades are available to enhance capability for delivering heavier ballistic and orbital payloads. 1 Copyright AIAA- 4th Responsive Space Conference All rights reserved. ACRONYM ATK Alliant Tech Systems AZ-50 Aerozine 50 CAV Common Aero Vehicle CONUS Continental United States COTS Commercial Off the Shelf DOT Department of Transportation EMA Electro-Mechanical Actuation F-15GSE F-15 Global Strike Eagle FTS Flight Termination System GSE Global Strike Eagle GTOW Gross-Take-Off-Weight ICBM Inter-Continental Ballistic Missile IOC Initial Operational Capability Ivac Vacuum Specific Impulse JATO Jet Assisted Take-Off LEO Low Earth Orbit LITV liquid injection Thrust Vector LOX Liquid Oxygen LV Launch Vehicle MIPCC Mass Injection Pre-Compression Cooling MSLV Micro Satellite Launch Vehicle NTO Nitrogen Tetroxide OTIS Optimum Trajectories by Implicit Simulation OTS Off-The-Shelf PW Pratt & Whitney RP Rocket Propellant SED-WR Scramjet Engine Demonstrator Wave Rider SRM Solid Rocket Motors UCAV Unmanned Combat Aerial Vehicle BACKGROUND The increasing dependence of both commercial and defense interests on space assets and the growing concern over the vulnerability of those assets forces a reassessment of our approach to space payload development and launch. Micro and Nano satellites combined with a responsive space launch capability can serve to bolster the 1 of 9

3 existing and future inventory of large satellites. While limits set by the dimensions and physical capabilities of Micro and Nano satellites preclude their usage for some applications. Micro- and Nano- satellites can supplant or augment large satellite performance in the following areas (Ref 1,5): Augmentation of existing constellations during conflicts Special purpose of limited scope missions Operate as distributed platforms Support space control concepts by providing additional platforms for defensive or offensive counter-space Space weather monitoring Low cost space technology testbed The reduced launch mass of Micro and Nano satellites shown in Table 1 coupled with the increasing capabilities afforded by miniaturized electronics and micro-electromechanical systems (Ref 3,4) creates an opportunity for an affordable low risk launch on demand system based on existing USAF air assets (Ref 2) with a spiral growth capability to accommodate mission growth. From Table 1, the launch mass for capable Micro and Nano satellites is less than 450 kilograms with additional reductions anticipated from continuing reduction in subsystem weight and power requirements. An F-15 based air launch system can provide multiple launch options spanning the range of interest. The utilization of Mini-satellite Micro-satellite Nano-satellite >450 kg kg kg XSS-10/11, OPAL, TacSat-1, JWS-2, Microsat-70/100, Minisat-400, Ofeq-3, MightySat II Globalstar, Quickbird, Iridium, StarBus, PegaStar DARPA Picosat, FalconSat, EyeSat, MegSat, SNAP, ST-5, Microstar Table 1 Micro and Nano Satellites Provide Useful Capability and Lower Launch Requirements the F-15 as the initial stage of the launch system provides not only the expected performance benefits reduced velocity requirements for the rocket stages, lower aerodynamic drag, and decreased atmospheric pressure but also the operational advantages inherent in using the existing support infrastructure. Mission operations benefit from flexible basing allowing multiple launch operations from geographically dispersed locations and the ability to fly out to intercept the optimum launch location and azimuth. Providing integrated payload and launch vehicle systems to existing USAF bases will allow early implementation of operationally responsive space capabilities. Various air launch concepts have been studied with the most recent U.S. studies focused on the F-15, C-17, B-1 and the BCA 747. Microsat launches using the F-15 as a launch platform for LEO would be available to all azimuths from a minimum of two CONUS bases (east and west coasts) or non CONUS bases (Hickam AFB, Guam, Australia, Diego Garcia, etc.). Global strike missions could be performed from a single ETR base and achieve near global coverage with CAV cross-range capability of 2500 nmi. F-15 GLOBAL STRIKE EAGLE CONCEPT Initial operations would utilize available F-15 C/D aircraft with high hours and an existing infrastructure to reduce operations cost. The F-15 C/D would provide an initial capability to launch small payloads constrained by the dimensional and structural load capability of the F-15. Additional analysis would be required to determine the aerodynamic and structural limitations of the F-15 C/D, although initial mass properties evaluation does not show carry weight to be a driver, for a 10,000 pound gross separation weight launch vehicle. Previous studies (Ref 6,7) have shown that this capability would be limited to approximately 100 2of 9

4 kg (220 lbs) for a F-15E variant. However, these studies utilize existing under-wing weapon pylons or the center-mount pylon for payload and launch vehicle (LV) carry. This type of conventional carry is convenient with minimum aircraft modification, however; limits the diameter and the length of LV hence limiting the mass of payload to orbit. An innovative concept was developed to extend the payload-to-orbit capability of the F-15E Strike Eagle, called the F-15 Global Strike Eagle (GSE), that utilize top mounted LV and payload instead of conventional under-carry. This eliminates the combined payload/ LV length limitation of center-pylon under-carry during the F-15 take-off. The F-15E strong back and wide tail span allow heavier and bigger diameter LV hence greatly enhance the mass of payload-toorbit. F-15 GSE The F-15 GSE, as shown in Figure 1, is a slightly modified from a F-15E that represents the most powerful heavy lift fighter aircraft in the U.S. inventory today. Equipped with two Pratt & Whitney (PW) F-100-PW-229 afterburning turbofan engines, each capable of 29,000 lbf thrust, with a maximum gross-take-off-weight (GTOW) of 81,000 lbm. It is capable of supersonic flight up to Mach 2.5 with service ceiling up to 60,000 feet. Figure 2 shows the configuration layout of the expendable upper stage LV on the F-15 GSE. The wide tail span and heavy lift characteristic of the F-15 enables this top mount concept for a higher payload delivery to orbit. Figure 1: F-15 Global Strike Eagle Specification Launch Vehicle The F-15 GSE concept uses existing off-theshelf (OTS) solid rocket motors (SRM) and/or government furnished from surplus ICBM SRMs, to reduce development cost and time to initial operational capability (IOC). Figure 3 show the 3 stage SRM booster used for the current study. Between booster stages, avionic control and communication packages, batteries, electro-mechanical actuation (EMA), sureseparation system and flight termination system (FTS) are installed. Aero-surfaces control fins are added for boost phase control. An Aft-Cone Body is added at the end of the booster for better aerodynamic characteristic during the F-15 boost phase, and is ejected shortly after the booster/ aircraft separation and before the first stage rocket ignition. Additional instrumentation will be added for initial flight test development data acquisition. 3of 9

5 The first stage uses the SR-19, from either the Minuteman II 2 nd stage or from the 2 nd stage of the Minotaur launch vehicle. It is capable of nominal vacuum thrust of 60, 300 lbf, with a vacuum specific impulse (Ivac) of seconds. Either additionally installed EMA for nozzle gimbal, or the existing liquid injection thrust vector (LITV) control that comes with the booster, can be used for the first stage TVC system. The 2 nd stage of the booster rocket uses the Orion 50XL, also an existing OTS SRM from the Pegasus XL 2 nd stage and/or the Minuteman 3 rd stage. The Orion 50XL has a nominal vacuum thrust of 34,500 lbf with an Ivac of 289 seconds. The 3 rd stage of the booster rocket uses the Orion 38, again an existing OTS SRM from the Pegasus XL 3 rd stage. The Orion 38 has a nominal vacuum thrust of 10,600 lbf and an Ivac of seconds. Both Orion 50XL and the Orion 39 are equipped with EMA gimbal actuation of the single flexseal nozzle from independent pitch and yaw actuators. Roll control is controlled by cold-gas jets located on the avionic structure. Figure 2: F-15GSE with Three Stage SRM Booster (LV) Figure 3 Solid Rocket Motor Boosters Used for F-15 GSE Launch Vehicle 4of 9

6 Figure 4 and 5 show typical trajectory profile of the F-15GSE using a 3 degree of freedom (3- DOF) simulation with the Boeing Huntington Beach version of the Optimum Trajectories by Implicit Simulation (OTIS) code for aircraft/rocket performance optimization. Three branches of flight regime were modeled: 1) Aircraft ascent to LV separation, 2) LV flight to mission target, and 3) Aircraft flyback to base. Existing F-15E aerodynamics and propulsion models, as well as mass properties data were supplied by Boeing-St. Louis and the SRM propulsion and mass properties data were supplied by the Alliant Tech Systems (ATK). Figure 4: Typical Trajectory Profile for F-15 GSE Mission F-15GSE/ LV Altitude Profile Figure 5: Typical Trajectory Profile for the F-15 GSE Mission - Launch Vehicle Altitude Profile Preliminary computational fluid dynamics (CFD) modeling was conducted on the F-15GSE/ LV configuration to ensure no aerodynamic showstoppers. The analysis indicates only minor 5of 9

7 reduction in F-15 lift due to the payload/ LV and increased vertical tail loading, which is compensated by a change of aircraft s angle of attack by 1 degree. (Figure 6). F-15E with Missile in Proximity F-15E Alone Figure 6 High Fidelity CFD Analyses Suggest F-15GSE is Devoid of Aerodynamics Show Stoppers F-15 GSE MODIFICATIONS Structural/ Mechanical Modifications The use of the F-15E for MSLV missions has shown adequate margin for centerline payloads up to 10,000 lbs (Ref 6). This analysis would need to be repeated to determine the centerline limits for the F-15 C/D. Usage of dedicated aircraft permits the elimination of nonessential equipment for increased payload capabilities and upgraded subsystems to support launch operations including payload external power, command uplink and telemetry downlink. Initial evaluation of the F-15 for top mounted missiles has shown that favorable attach points exist for attachment of a new pylon (Figure 7). Benefits of the top mount include the elimination of dimensional restrictions associated with landing gear and ground strike and compressive loads rather than tension loads during pull-up maneuvers and landing. Avionic/ Software/ Flight Control Systems Required modifications to support the F-15GSE concept can range from little to no modification to the existing avionic, software and flight control systems for the F-15 C/D version with under-wing or centerline carry of MSLV, to the F-15 GSE version with top-carry of larger LV and payload. Top carry allows a nesting configuration of the LV for reduced drag. The F-15 GSE version with larger LV impairs pilot ejection capability and would therefore be unmanned. Existing flight control software and communications links available for UCAV such as the X-45 or X-36 would be used to allow unmanned operation. Figure 7: Four Primary Bulkheads Provide 8 Robust Attach Points for Pylon Attachment 6of 9

8 F-15 GSE BENEFITS The F-15 GSE offers the following benefits: Capability for near term operationallysignificant missions. Operationally responsive space and munitions launch Improved performance & flexibility. o 5,000 fps delta-v reduction for expendable upper stages vs. ground launch. o All azimuth launch capability. o Low mission profile looks just like another F-15. o Mission flexibility. Forward basing options (can be based anywhere). Recall capability. Blue suit operation. Low system development cost, risk and schedule. o Existing assets, infrastructure, maintenance personnel and training. o Minimum modification required for adapting F-15E to F-15GSE (maintain ability to return to service). Initial demonstration possible with COTS subsystems and potential for government furnished solid motors. o Unmanned F-15 eliminates restrictions and complexity associated with LV deployment. o Low-risk platform for developing DARPA FALCON-like technologies. Hypersonic test bed for DARPA technologies Separation demonstrator for Hybrid Launch Vehicle (HLV) concepts supporting Affordable Responsive Spacelift (ARES) Spiral upgrades for higher payload delivery o Initial limited capability using F-15 C/D with underwing or centermount (MSLV) launch vehicle o Performance growth option to F-15 C/D top mount o Performance growth option with modification of F-15 C/D or F-15E utilization o Performance growth option with UAV enhancement to F-15 o Performance growth option with F-15 propulsion augmentation. o Optimized Upper Stage with solid, hybrids, or liquid propulsion stages. 7 of 9 F-15 GSE PAYLOAD GROWTH OPTIONS F-15 E/F version and engine upgrade Further spiral development could use the F-15 E/F to allow for LV mass as large as 30,000 lbs. This capability enables launching global strike missions of 1200 lbs to 10,000 nm and microsats of 273 kg (600 lbs) to 100 nmi at 28.5 degrees. F-15 MIPCC and other growth options Additional performance can be gained with future growth version of the F-15. Performance enhancement on the F-15 can either further reduce the delta-v required by the LV or to provide bigger payload to orbit. Simple JATO (jet assisted take-off) boosters can be attached to the F-15 to increase its takeoff capability. Advanced propulsion enhancement technology, such as the mass injection pre-compression cooling (MIPCC) technique, can be used to further enhance the F-15 performance in both thrust and altitude achievable. MIPCC was studied under DARPA RASCAL program and is currently being ground tested for the X-51 scramjet engine demonstrator wave rider (SED-WR) program. Liquid Rocket Boosters for LV The initially available COTS already integrated Minotaur SRMs permit a low risk fast paced schedule to demonstrate the F-15GSE concept, with the capability for immediate, operationallysignificant missions. If larger payload delivery capability is desired as a growth option, the use of liquid propellants for the LV can offer performance improvements due to the generally higher Ivac values. Figure 8 shows the potential payload benefits with liquid propellants for the LV. The fueling and storage of liquid propellants must be considered as an operational issue. The storable liquid propellants, such as nitrogen textroxide (NTO) and aerozine 50 (AZ- 50), can be pre-filled and sealed at factory, meeting the DOT requirements for ground and air transport as well as eliminating the task of pre-launch fueling, have an operational advantage over cryogenic propellants such as using liquid oxygen (LOX) and kerosene (RP) system. These propellant options, offer performance advantages, with operational impacts to responsive launch which must be addressed in future studies.

9 Figure 8: Liquid Propellants Increase F-15 GSE Payload Capability to DARPA FALCON Requirement DEVELOPMENT PLAN & SCHEDULE Internal studies support a development plan with a 30 month preliminary and detail design phase followed by a 10 month flight test program using a simulated launch vehicle to validate separation dynamics and F-15 flight performance. Launch vehicle development, integration and test to replace the simulator would add 12 months to the schedule with some schedule savings possible if launch vehicle development is planned as a parallel development. ACKNOWLEDGEMENTS This work was done under Boeing IDS Internal Research and Development Fund. The authors wish to acknowledge the following team member contributions: Tom Mead, Billy Burroughs, Greg Larson, Richard Hora, Curt Wiler, Todd Magee, and Peter Hartwich. We also wish to thank Ted Ralston for the review, advice and critique. CONCLUSION The concept of air launch using existing F- 15C/D version with growth path to F-15E as the F-15 Global Strike Eagle (GSE) is addressed. A novel configuration of carrying the LV and payload, on top of F-15E enables larger payload delivery to LEO, or a 10,000 mile cross-range capability. The F-15GSE provides a near term capability for immediate, operationally-significant missions, such as tactically responsive space and munitions launch for prompt global strike capability. It combines improved performance & mission flexibility with low system development cost, risk and schedule, with various growth options for further improving its payload performance. 8 of 9

10 REFERENCES 1. Bille, M., Kane, R., Nowlin, M., Military Microsatellites: Matching Requirements and technology Paper No. AIAA , AIAA Space 2000 Conference and Exposition, Long Beach, California, September Moser, R., Collins, D., Das, A., Ferber, R., Jaivin, G., Madison, R., Smith, J., Stallard, M., Novel Missions for Next Generation Microsatellites: The Results of a Joint AFRL-JPL Study Paper No. SSC99-VII-I, 13 th Annual AIAA/USU Conference on Small Satellites, Logan, Utah, August Panetta, P.V., Culver, H., Gagosian, J., Johnson, M., Kellogg, J., Mangus, D., Michalek, T., Sank, V., Tompkins, S., NASA/GSFC Nano-Satellite Technology Development in Science Closure and Enabling Technologies for Constellation Class Missions edited by Angelopoulos, V. and Panetta, P.V., pages , U.C. Berkeley, California, Martin, M., Klupar, P., Kilberg, S., Winter, J., TECHSAT 21 and Revolutionizing Space Missions Using Microsatellites, SSC01-1-3, American Institute of Aeronautics and Astronautics 5. Pimprikar, M., Srivastava, D., Mehrez, H., Ferrer, C., Hicks, P., 2002 Micro-Nanotechnology for Space Applications, Centre for Large Space Structures and Systems (CSL3) 6. Capt. Nick Hague, Lt. Erika Siegenthaler, Lt. Julia Rothman, Enabling Responsive Space: F-15 Microsatellite Launch Vehicle, Vol , American Institute of Aeronautics and Astronautics 7. Launch on Demand Booster Study, The Aerospace Corporation 9of 9